I hate abusing all these dead Equidae, so this will be my last post to the list on this. Geo and I will settle it 'underground' lest this become another bolide/fireball episode. Also, Bernd seems to be having trouble getting on line to respond.
Parallelism can refer to 'a similar course'. Bernd's induction
of the 'classical' example pertaining to railroad tracks holds in this
case only with regard to perspective, not to the definition
of 'parallel' regarding lines that never meet.
My anaylsis of our communcation problem is that, while orbits can be
parallel elliptical or concentric, orbits containing many grain sized objects
demand the use of the broader definition of 'travelling in a similar
course (parallel)'- just don 't invoke the RR track example.
It was intended to convey perspective and true parallel lines that never
meet.
Now we could really have some fun if I hop on a train travelling at a velocity of 90mph headed due West, Geo floats down the Mississppi at 10 knots (boat optional) and Bernd lassos the closest comet* in time to observe both us and the showers to give us all true perspective.
Hubble, where are you when I need you?
Best regards,
Julia
*This could have been funny if I had only interjected the closest comet's
name, but in sticking with my hard and fast rule never to do my homework,
I again sacrifice the quality of my work. Oh well.